1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
import { assertEquals } from "../testing/asserts.ts";import { groupBy } from "./group_by.ts";
function groupByTest<T>(  input: [Array<T>, (el: T) => string],  expected: { [x: string]: Array<T> },  message?: string,) {  const actual = groupBy(...input);  assertEquals(actual, expected, message);}
Deno.test({  name: "[collections/groupBy] no mutation",  fn() {    const arrayA = [1.1, 4.2, 4.5];    groupBy(arrayA, () => "test");
    assertEquals(arrayA, [1.1, 4.2, 4.5]);  },});
Deno.test({  name: "[collections/groupBy] empty input",  fn() {    groupByTest(      [[], () => "a"],      {},    );  },});
Deno.test({  name: "[collections/groupBy] constant key",  fn() {    groupByTest(      [[1, 3, 5, 6], () => "a"],      { a: [1, 3, 5, 6] },    );  },});
Deno.test({  name: "[collections/groupBy] empty key",  fn() {    groupByTest(      [        ["Foo", "b"],        (it) => it.charAt(1),      ],      {        "o": ["Foo"],        "": ["b"],      },    );  },});
Deno.test({  name: "[collections/groupBy] groups",  fn() {    groupByTest(      [        ["Anna", "Marija", "Karl", "Arnold", "Martha"],        (it) => it.charAt(0),      ],      {        "A": ["Anna", "Arnold"],        "M": ["Marija", "Martha"],        "K": ["Karl"],      },    );    groupByTest(      [        [1.2, 2, 2.3, 6.3, 6.9, 6],        (it) => Math.floor(it).toString(),      ],      {        "1": [1.2],        "2": [2, 2.3],        "6": [6.3, 6.9, 6],      },    );  },});